Effects of an additional iron injection on growth and humoral immunity of weanling pigs

In a 5-week study, 120 crossbred weaning pigs (age 4 weeks) were used to ex amine the effects of an additional Fe-injection and immunization moment on the growth and humoral immune response. Pigs were allotted to one of eight treatments based on body weight and litter origin. Factors included: (1) si ngle intramuscular injection (day 3 after birth) vs. double intramuscular i njection (days 3 and 21 after birth) of 200 mg Fe; (2) antigen challenge (K eyhole limpet hemocyanin (KLH) and ovalbumin (OA) vs. placebo); and (3) imm unization moment (day - 1 vs. 1 after weaning). All pigs had free access to prestarter. diets supplemented with 80 mg kg(-1) Fe as FeSO4 . 7H(2)O. Pig s were housed in a room consisting of 12 pens (ten pigs per pen). During th e experiment, blood hemoglobin (Hb) levels and body weight were determined weekly and total Ig, Ige and IgM titers to KLH and OA twice a week. At day 6 after weaning, the blood Hb levels of double injected pigs were higher (P < 0.01) than the blood Hb-levels of the pigs that had received a single Fe -injection. Prior to day 6 and thereafter, blood Wb levels were similar bot h for single and double injected groups. Throughout the experiment, the add itional Fe-injection, and immunization moment had no effect (P > 0.1) on gr owth and total Ig response to KLH and OA. But the genotype of the pigs affe cted (P < 0.05) the kinetics of the total Ig response to KLH and OA. In con clusion, an additional injection of Fe one week prior to weaning does not a ffect body growth, and does not enhance or support the humoral immunity to a T-cell dependent antigen. Furthermore, the suppressing effect of weaning on humoral immunity was not affected by additional Fe. (C) 2000 Elsevier Sc ience B.V. All rights reserved.